Underground metro stations are inhumanely warm come sun or rain, so it makes sense for builders of a new housing estate in Paris to want to draw from that energy, harnessing it for 17 apartments' heating systems above-ground.

It's not just heat from the trains which can be used for generating heating "upstairs"—according to Planet Ark, each passenger expels 100W of energy down there on the platforms. Even in the morning crush, that's a heck of a lot of energy, which can be routed up from the metro station into the building through an existing staircase—meaning the structural design of the station won't have to be altered, only heat exchangers and pipes added. It's expected to be finished by next year, so if any Parisian readers are looking for new accommodation near the Pompidou museum, hit up the relevant real estate agency. [Planet Ark via Inhabitat]